The present invention relates to a data reception and transmission method that controls recording and playback devices for disks, tapes, or the like via a digital interface.
In recent years, the IEEE (The Institute of Electrical and Electronics Engineers, Inc.) 1394 method has been attracting attention as a serial transmission method. The IEEE 1394 method can be used not only for the transmission of computer data traditionally supported by SCSI (small computer system interface) and other systems, but also for the transmission of AV data such as audio and video data. This is because two communication methods, asynchronous and isochronous, are defined for the IEEE 1394 method. Isochronous communication is a data transmission method that can be used for the transmission of data such as AV data that has a real-time requirement. In isochronous communication, the bandwidth required for the transmission of data is secured prior to the initiation of the transmission. Then, the data transmission is performed using the thus secured bandwidth. This ensures the real time transmission of the data. Asynchronous communication, on the other hand, is a transmission method used for the control of devices and the transmission of data such as computer data that does not have a real-time requirement.
Various methods have been proposed to provide transmission protocols for IEEE 1394. One of them is a protocol called the AV protocol. The AV protocol is expected to be standardized as IEC (International Electrotechnical Commission) 61883, and defines such methods as isochronous transmission and reception of time-critical AV data and asynchronous transmission and reception of commands to be given to devices.
IEEE 1394 uses a concept called xe2x80x9cplugxe2x80x9d in order to handle the input and output of AV data in AV playback devices or recording/playback devices for compact discs (hereinafter CDs), minidiscs (hereinafter MDs), etc. The plugis a virtual connection terminal between AV devices, and is responsible for the transmission and reception of isochronous communication data, asynchronous communication data, etc. In a combination device incorporating a plurality of functions into one unit, the plug may be provided for each function unit. For example, a combination CD and radio cassette player/recorder is considered to be a combination of the various function units, i.e., the CD player, the tuner (radio), and the cassette tape recorder.
There are two types of plug: the receiving plug for receiving data from the outside and the transmitting plug, for transmitting data to the outside. These plugs have their own attributes and operating states. In the AV protocol, however, no methods are defined for handling information concerning these plugs. In view of this, there have been proposed a method of holding these pieces of information in a list structure and a method of externally accessing the list. One example is the AV/C DISC Subunit Proposal version 0.7 presented at the IEEE 1394 Trade Association (hereinafter TA).
The plug is a virtual and functional concept for handling AV data, and does not refer to a physical terminal itself on the IEEE 1394 bus. In some cases, the plug may directly handle the data of an analog input/output terminal or data of an optical input/output terminal that handles ICE 958 data.
The IEEE 1394 bus is capable of transmission at 100, 200, and 400 Mbps with a single terminal; for comparison, the linear PCM signal used for input and output of MD, for example, is 1.4 Mbps for two channels. This means that one IEEE 1394 terminal has a sufficient capacity to handle both input and output simultaneously. Furthermore, device control signals can also be handled at the same time. In the following description, the receiving plug, the transmitting plug, and control signals are described as if they were independent terminalis, but it will be noted that the plug is nothing but a virtual and functional concept, and that the number of IEEE 1394 terminals physically mounted on an actual device is one or two or so (for the cascading of devices).
The prior art plug information handling proposed in the above draft of standard (AV/C DISC Subunit Proposal version 0.7) will be described below with reference to drawings.
FIG. 5 is a block diagram showing a recording and playback disc subunit according to the prior art. One or a plurality of such subunits together constitute one device. In FIG. 5 reference numeral 401 is the disc subunit (hereinafter sometimes referred to simply as the subunit), 402 is a receiving plug, 403 is a transmitting plug, 404 is a description structure called a descriptor, and 405 is a state list, included in the description structure 404, for showing the state of the subunit. FIG. 5 assumes the use of MD; therefore, one receiving plug and one transmitting plug are provided. Here, a stereo signal can be handled by one plug.
The description structure 404 includes attribute information and state information of the subunit 401, attribute information and contents information of media, etc. in the form of a list structure, and is used to transmit/receive information between subunits. The details of how reading and writing is performed on each list are described in the AV/C Digital Interface Command Set General Specification published by the IEEE 1394 TA.
FIG. 6 is a diagram showing the structure of the state list 405 included in the description structure 404 for showing the state of the subunit. The state list 405 is stored in a memory within the subunit, but here it is shown like a hierarchical structure to show the contents in simplified form.
The state list 405 comprises four broad categories: (1) list length, (2) general state, (3) receiving plug state, and (4) transmitting plug state.
The list length (1) indicates the length of the state list 405. Since the description structure 404 is made up of a plurality of lists, this list length is used to compute the starting address of the list that follows the state list 405. The general state (2) stores general information concerning the subunit, such as information indicating whether a medium is in the subunit, and in the case of a device error, the cause and the last executed command.
The receiving plug state (3) includes the number of receiving plugs (m) and the receiving plug state [x] (x=1 to m). In the illustrated prior art example, since the number of receiving plugs is one, only one receiving plug state is shown. The receiving plug state [x], whose detailed contents are shown at 406 in FIG. 6, consists of five portions, (a) receiving plug state length, (b) receiving plug number, (c) operating mode, (d) current position, and (e) plug setting.
The receiving plug state length (a) indicates the length of the receiving plug state portion. The receiving plug number (b) shows the identification number of the receiving plug. The operating mode (c) will be described in detail later. The current position information (d) indicates the current record position (music track number, etc.) on the medium currently associated with the receiving plug. How this is done depends on the media recording format; in the case of MD, the position is indicated by the track number and by hours:minutes:seconds:frames from the beginning of the track. In the plug setting portion (e) are stored a list identifier in the media recording hierarchy (in the case of MD, this automatically is a route list since MD does not have a recording hierarchical structure), recording format (audio, video, MIDI, still image, etc.), and detailed information concerning the recording format (in the case of audio, sampling frequency, sampling bit length, compression scheme, number of recording channels, etc.). The plug setting comprises one that beforehand the subunit has as unique values and is not alterable from the outside (for example, MD sampling frequency, sampling bit length, compression scheme, etc.) and the other that is alterable from the outside depending on the subunit (number of recording channels: selection between monaural and stereo, for example).
The operating mode (c) will be described in detail below. Table 1 shows the operating mode and operating mode specific information. The operating mode for the receiving plug is classified into three modes, STOP, RECORD, and SUSPEND, with two subfunctions provided for RECORD and reasons attached to SUSPEND.
The RECORD subfunction 1 xe2x80x9cTIME MACHINExe2x80x9d is a function that starts recording from input data which is stored in MD memory and is before receiving a record command. The subfunction 2 xe2x80x9cNEWxe2x80x9d is a mode for newly recording in an unrecorded area of the disc, while xe2x80x9cOVERWRITExe2x80x9d is a mode for overwriting an already recorded area.
Of the suspend reasons, xe2x80x9cNO MEDIAxe2x80x9d indicates that the subunit is not in a condition ready for loading or unloading a medium (in the case of a tray type device, the tray is closed) and no media are loaded into it.
xe2x80x9cREADING TOC (Table of Contents, data concerning areas where the contents of the MD are stored)xe2x80x9d indicates that the subunit is automatically reading the TOC, for example, when a new medium is loaded into the subunit. xe2x80x9cWRITING TOCxe2x80x9d indicates that necessary writing process is being done to the TOC when the contents of the medium are altered, for example, when audio data is recorded or when an edit command is executed. The timing to actually write the TOC depends on the device. In some devices, writing is done to the TOC immediately after the contents of the medium are altered, and in others, the altered contents are stored in a semiconductor memory or the like within the device, and writing is done to the TOC when a command for unloading the medium or a command for turning off power is received.
The suspend reason xe2x80x9cCAPACITY EXCEEDxe2x80x9d indicates that in a device such as an HDD (hard disk drive) capable of handling a plurality of streams using one head, the necessary transmission capacity cannot be secured for the stream that the plug is going to handle because of already input or output streams. Accordingly, this reason need not be indicated in the case of MD, etc. that include only one input and one output.
The operating mode can be divided between modes (RECORD, STOP, etc. )that are controlled by externally entering special operation commands and modes (SUSPEND/READING TOC, RECORDING STOP due to media recording capacity full, etc.) that the subunit automatically effects. The operating mode can only be read from the outside and cannot be written directly.
The transmitting plug state (4) in the state list 405 consists of six portions, (a) transmitting plug state length, (b) transmitting plug number, (c) operating mode, (d) current position, (e) recording format, and (f) plug setting (see Table 2).
Operating mode: The operating mode specific information for SEARCH indicates the position to be searched for.
Track relative time: A search command such as xe2x80x9cSearch for the 40-second position in track 4xe2x80x9d.
Absolute time: Indicates the time from the beginning of the entire contents.
Relative unit: Specifies how many units after or before from the unit currently being played back (the unit is the contents unit corresponding to the track on MD or CD.
Absolute unit: Specifies a unit as counted from the beginning of the entire contents.
Next, an example of the case where data is recorded using the plug will be described below. In the example described here, a CD player is used as the transmitting device and an MD recorder as the receiving recording device, and these devices are controlled by an external controller. In this prior art example, data played back on the transmitting device (CD player) is recorded by the receiving device (MD recorder) in the xe2x80x9cNEWxe2x80x9d mode.
FIG. 7 shows the connections of the controller 701, the transmitting device (CD player) 702, and the receiving device. The controller 701, the transmitting device (CD player) 702, and the receiving device (MD recorder) 703 are connected by a serial bus 704. The transmitting device (CD player) 702 contains a disc subunit (CD) 705, and outputs isochronous data on the serial bus 704 via a transmitting plug 706. The receiving device (MD recorder) 703 also contains a disc subunit (MD) 707, and receives isochronous data from the serial bus 704 via a receiving plug 708. Control data also is transmitted to each subunit via the serial bus 704. Control data packets each carry an address specifying the destination device, and only the specified device processes the packet. The path for transmitting/receiving the control data between the serial bus 704 and each subunit is not specifically shown by Figures.
FIG. 8 is a diagram showing the transmit/receive of control signals among the disc subunit (MD) 707, the controller 701, and the disc subunit (CD) 705. First, (1) the controller 701 makes detailed settings for the disc subunit (CD) 705 as the transmitting device. More specifically, the settings include the setting of a play list (a list specifying the sequence of playback in programmed playback mode), the designation of the playback positions, and the setting of the transmitting plug 706. These settings are respectively made using special commands, to each of which the disc subunit (CD) 705 returns a response, such as setting completed or denied, to the controller 701. For simplicity, the response is shown here represented by setting completed (2).
Next, the controller 701 issues a subunit state read request (3) to request and read the state of the disc subunit (MD) 707. The disc subunit (MD) 707 returns the contents of the state list as state information (4) to the controller 701. Here, it is assumed that the operating mode of the disc subunit (MD) 707 is xe2x80x9cSTOPxe2x80x9d. Since the operating mode of the disc subunit (MD) 707 is xe2x80x9cSTOPxe2x80x9d, the controller 701 can determine that recording will be possible in the xe2x80x9cNEWxe2x80x9d mode. Then, (5) the controller 701 makes detailed settings for the disc subunit (MD) 707 as the receiving plug. More specifically, the settings include the setting of recording channels (monaural or stereo), etc. The disc subunit (MD) 707 returns setting completed (6) to the controller 701 as a setting completed notification. The controller 701 sends a record request (xe2x80x9cNEWxe2x80x9d mode) (7) to the disc subunit (MD) 707 to request recording. The disc subunit (MD) 707 returns recording started (8) to the controller 701 as a recording started notification. At this time, the operating mode of the disc subunit (MD) 707 changes from STOP to RECORD.
The controller 701 sends a transmit request as a data transmit request (9) to the disc subunit (CD) 705, and the disc subunit (CD) 705 starts transmitting data to the disc subunit (MD) 707 as indicated by data transmission (10), while at the same time, sending a transmission started notification (11) to notify the controller 701.
With the above sequence of operations, data from the disc subunit (CD) 705 is recorded on the disc subunit (MD) 707.
However, the above conventional method has had the problem that when the operating mode of the subunit is SUSPEND, there are no set rules defining in what sequence the reasons for suspend are to be displayed or which reason is to be displayed in preference to others.
For example, when the digital input signal is an audio bit stream defined by IEC 958, if the PLL (phase locked loop) for reproducing the clock for the input signal is not in lock, the input signal can neither be handled nor be recorded as a matter of course; since the out-of-lock condition is a very important reason for suspend, such a reason must always be displayed in preference to any other reason, but this was not always the case with the prior art.
The present invention has been devised to overcome the above problem, and provides a data receiving device and a data transmitting device wherein each suspend reason is classified in advance so that an important reason can be displayed in preference to others.
Accordingly, the present invention is a signal data receiving device for at least receiving data via a digital interface, comprising:
receiving terminal data holding means for holding data concerning a state of a terminal via which data is received, and wherein
said terminal state data includes terminal operating mode information,
suspend reasons concerning suspend in said operating mode information are classified using at least a receiving data state and a device operation state as classification criteria, and
these classifications and each classified suspend reason are capable of being displayed on another device connected to said digital interface.
Further, the present invention is a signal data transmitting device for at least transmitting data via a digital interface, comprising:
transmitting terminal data holding means for holding data concerning the state of a terminal via which data is transmitted, and wherein
said terminal state data includes terminal operating mode information,
suspend reasons concerning suspend in said operating mode information are classified using at least a transmitting data state and a device operation state as classification criteria, and
these classifications and each classified suspend reason are capable of being displayed on another device connected to said digital interface.
Still further, the suspend reasons of the present invention are displayed according to priority predetermined among said classification criteria.
In this way, when a plurality of suspend reasons occur simultaneously, the suspend reasons are selectively displayed according to the predetermined priority.